Friday, June 26, 2015

Artist's conception of the lunar dust exosphere surrounding the moon. The color represents the amount of material ejected from the surface, showing a peak in the apex direction. A haze of dust is shown around the moon. Gray faded circles are overlaid on the lunar surface to represent the random nature of the primary impactors. An artist's conception of the LADEE orbital inclination is also shown [UC Boulder/Daniel Morgan/Jamey Szalay].

Darryl Waller

Sharon Lozano

NASA Ames

New science results from NASA’s LADEE mission (Lunar Atmosphere and Dust Environment Explorer) indicate the Moon is regularly engulfed in a permanent, but lopsided and transitory, dust cloud increasing in density during encounters with cometary debris, like those producing the Geminids, according to a new study led by University of Colorado Boulder.

"Knowledge about the dusty environments in space has practical applications," said CU-Boulder physics Professor Mihály Horányi. "Knowing where the dust is and where it is headed in the solar system could help mitigate hazards for future human exploration, including dust particles damaging spacecraft or harming astronauts."

The cloud was discovered using data from a detector on board LADEE called the Lunar Dust Experiment (LDEX) designed and built by CU-Boulder. LDEX charted more than 140,000 impacts during the six-month survey launched in September 2013. NASA’s Ames Research Center in Moffett Field, California was responsible for spacecraft design, development, testing and mission operations.

“The LDEX team has been painstakingly analyzing their data since the LADEE mission ended on April 18, 2014,” said LADEE project scientist at Ames, Rick Elphic. “Their results answer one of the big LADEE science questions: is there a dust component to the tenuous lunar atmosphere? And if so, why is it there?”

According to Horányi, the cloud is primarily made up of tiny dust grains kicked up from the moon’s surface by the impact of high-speed, interplanetary dust particles. A single dust particle from a comet striking the moon’s surface lofts thousands of smaller dust specks into the airless environment, and the lunar cloud is maintained by this sometimes predictable process of regolith "gardening."

“Identifying this permanent dust cloud engulfing the moon was a nice gift from this mission,” said Horányi, the principal investigator for the LDEX instrument and lead author of the study. “We can carry these findings over to studies of other airless bodies, like the moons of other planets and the asteroids.”

A paper on the subject appears in the June 17 issue of Nature. Co-authors Jamey Szalay, Sascha Kempf, Eberhard Grun and Zoltan Sternovsky from CU-Boulder, Juergen Schmidt from the University Oulu in Finland, and Ralf Srama from the University of Stuttgart in Germany.

The first hints of a cloud of dust around the moon came in the late 1960s when cameras functioning overnight aboard the unmanned moon lander Surveyor 7 captured bright glow hours ahead of lunar sunrise. Not long after astronauts in lunar orbit described a significant glow above the lunar surface when approaching sunrise, phenomenon brighter than the sun by itself should have been able to produce over a body with only a trace, essentially non-existent, atmosphere.

Because these new findings do not square with the Apollo reports of a thicker, higher dust cloud, conditions back then may have been somewhat different. The dust on the moon -- which is dark and sticky and regularly dirtied the suits of moonwalking astronauts -- was created over several billion years as interplanetary dust particles incessantly pounded the rocky lunar surface.

Many of the cometary dust particles impacting lunar surface are traveling at thousands of miles per hour in a retrograde, or counterclockwise orbit around the sun, the opposite orbital direction of the solar system’s planets. This causes high-speed, near head-on collisions with the dust particles and the moon’s leading surface as the Earth-moon system travel together around the sun.

Monday, June 22, 2015

This is perhaps the premier conference on space resource utilization, space mining, granular mechanics in space, etc. Springtime in Orlando figuring out how to extend human civilization into the solar system - what could be better?